Keyboard touch feature



- Oct. 28, 1958 Filed June 16, 1954 W. A. HElDT ETAL KEYBOARD TOUCH FEATURE 5 Shets-Sheet 1 IN VEN TORS WILLIAM A ElDT C E H HARL A. M ULLE R BY mmruo ATTORNEY Filed June 16, 1954 Oct. 28, 1958 'w. A. HEIDT ETAL KEYBOARD TOUCH FEATURE 3 Sheets-Sheet 2 INV 0R8 WILLIAM A. DT B CHARL SA. MULLER ATTORNEY Oct. 28, 1958 HEIDT A 2,858,002

KEYBOARD TOUCHFEATURE Filed June 16, 1954 3 Sheets-Sheet 3 055m PE xau *0 on: 52:! 53 22:0 E 5953 -22 Ex 0 n53 02:0 5 mEo on 32: L

.53. 9. 3 396cm 2 gram 32:55 on 5 3 u Econ: 8.2a =22 at... 0

nEou 02:0 5 32 3 -22 3x SEIONHO INVENTORS WILLIAM A.HE|DT BY CHARLES A. MULLER ATTORNEY United States Patent KEYBOARD TOUCH FEATURE William A. Heidt, Poughkeepsie, and Charles A. Muller, Wappinger Falls, N. Y., assignors to International Business Machines Corporation, New York, N. Y., a corporation of New York Application June 16, 1954, Serial No. 437,104 Claims. (Cl. 197-17) This invention relates to typewriters of the power driven class, and more particularly to an improved resilient support for the movable end of a pivotable key lever employed for actuating a type bar drive mechanism.

It has been found through years of typewriter development that an actuating key lever should be positioned for movement from an inoperative position through an actuating range, and then beyond that range and in the same direction through a non-functioning stage. The movement through the non-functioning stage, however, is a wasted movement and the operator should be encouraged to remove her finger from the key as soon as possible after the lever enters the non-functioning stage. In this respect, it should be noted that a key lever stroke should not be terminated abruptly by a mechanical stop exactly at the end of a function stroke, otherwise the operator would in elfect, receive a number of hammer blows on her finger tips that eventually would cause pain and numbness. Accordingly, the non-functioning movement is provided wherein the operator has opportunity to slow down her finger speed before the key lever strikes a mechanical stop, thereby reducing the impact shock.

A trained typist can sense the end of a function stroke, and reduce her finger speed before the mechanical stop is encountered, but an improved signalling medium is required for indicating the termination of a function stroke, and it is an object of this invention to provide.

such an improved signalling medium for indicating the termination of a key lever function stroke.

It is a further object of this invention to provide an improved resilient support device for signalling the end of a key lever function stroke, and for resiliently absorbing the shock of a typist finger stroke.

It is a further object of this invention to provide a mechanism for increasing the typists speed of operation by providing a resilient stop for a key lever which stop takes effect after the functioning stroke of the key lever has been completed, and acts as a springboard to help the typist lift her finger from a key after it has completed its function stroke.

Other objects of the invention will be pointed outin the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. 1 is a side elevation of a type bar actuating mechamsm.

Fig. 2 is a side elevation of the same type bar actuating mechanism with the operating parts displaced from their rest position.

Fig. 3 is an enlarged side elevation of a portion of a key lever guide comb; while Fig. 4 is a graph of the forces acting on a typewriter key lever during a print stroke.

Briefly, this invention relates .to an improved resilient stop for one end of a typewriter. key lever wherein an unloaded auxiliary spring is positioned for engagement 2,858,002 Patented Oct. 28, 1958 with a key lever after it has finished its function stroke, and while travelling through its non-functioning range.

With reference to the drawing, a type bar 1 is shown positioned for operation in response to depression of a key lever 2 through an interconnecting structure comprising a link 3, a cam lever 4, a cam 5 and a trip latch 6. The type bar 1 is pivoted about the usual hoop shaped shaft 7 for rotation from a rest position (e. g. from a basket 8) to the platen 9 for a print stroke. Cam lever 4 is positioned for pivotal rotation about a transverse shaft 10 which extends across the typewriter. The rotation of cam 4 about shaft 10 actuates its associated type bar 1 to rotate the latter about shaft 7 through means of link 3 which interconnects the head 11 of cam lever 4 and a sub lever 12, an integral part of the type bar 1. Cam lever 4 is biased by a spring 13 in a direction to restore it to its normal or rest position as shown in Fig. 1.

To effect movement of the cam lever 4 about shaft 10, cam 5, which has a serrated tread 15 is mounted for angular movement on a pivot or shaft 16 supported by the cam lever 4. A cam spring 17 extends between a loop 18 on the cam 5 and an ear 19 of the cam lever 4 to bias cam 5 normally counterclockwise about its pivot to its disengaged positionshown in Fig. 1 wherein the serrated tread 15 is just out of engagement with the periphery of the power roll 20. The latter, incidentally,

clockwise rotation of the trip is driven by some motor source (not shown) for rotation at a constant rate and in a counterclockwise direction as viewed in Fig. 1.

The serrated tread 15 of cam 5 is eccentric with respect to pivot 16 and accordingly, when the tread is brought into engagement with the power roll 20, the resulting frictional drive causes the cam 5 to swing upwardly and clockwise about its pivot 16, thereby forcing the latter outwardly from the power roll and clockwise about stud 10. This clockwise movement of stud 16 naturally rotates cam lever 4 about shaft 10 to actuate the type bar 1 for a print stroke.

During a print stroke, and at the point where the stud 16 is removed from the power rolls peripheral surface, a distance greater than the maximum radius of cam 5, then the frictional drive between the power roll and the serrate tread ceases, and the spring 17 acts to rotate the cam 5 counterclockwise about the stud 16 to its normal or rest position relative to cam lever arm 4. This disengagement between the tread 15 and power roll 20 always takes place before a type bar strikes the platen.

In order to initiate a type bar print stroke, the serrate tread 15 of cam 5 must be brought into engagement with the. peripheral surface of the power roll 26. In the disclosed embodiment, a trip, latch or plate 6 is employed to initiate this engagement. The latch is supported for both pivotal and sliding motion with respect to a stud 23 which is carried by the cam lever 4. Specifically, the trip latch 6 has an elongated or generally elliptical aperture 24 for mounting on stud latch, simultaneous counterclockwise pivotal movement and sliding movement downward to the right as viewed in Fig. 1. A latch spring 25 which is interconnected between an ear 26 on cam lever 4 and. an ear 27 on the latch 6, normally pulls the trip latch 6 upwardly and clockwise about stud 23 into the position shown in Fig. 1.

The trip latch 6 carries a cam car 28 positioned for engagement with the actuating or camming surface 29 on the cam5. It is readily apparent that any counterlatch 6 about its support stud 23 causes the cam ear 28 to push on camming surface 29 and thereby rotate cam. 5 clockwise about stud 16 to force the serrated tread 15 into engagement with A the periphery of power roll 20.

23 to provide, for the trip In order to rotate the latch 6 an operating lug 30, is positioned onthe key lever 2- for engagement with akey ear 31 carried by the latch 6. The key lever, which is supported for rotation about a ,shaft 32, is so positioned that any clockwise, angular movementof the-key ,lever about its support shaft 32, causes lug30 to act on key car 31 to rotate the plate 6 about its pivot23 bringing cam 5 into engagement with the power roll thereby to initiate a type bar print stroke.

The outer end of the key lever is supported .for controlled movement in a guide comb'33 which has a plurality of individual parallel guide slots 34, each having a length great enough to permit the-desired pivotal movement of the key lever. Each key lever has atits outer extremity, a hooked end 35, which holds one end of a restoring spring 38. The other end of the spring 38 is mounted on a suitable finger 36 forming a portion of the guide comb 33. With this structure, the restoring spring38 tends to maintain each key lever in its retracted or normal position as shown in Fig. 1.

Reference is now made to Fig. 2, wherein the key lever 2 isshown depressed to initiate a type bar stroke. Operating lug 30 has rotated trip latch 6 about stud 23 to bring the serrated cam tread 15 into peripheral .contact with power roller 20. After this arrangement of parts has been reached, the cam 5 is driven by the power roll about the stud 16 and the continually increasing radius between stud 16 and the serrated tread 15, forces the stud 16 clockwise about shaft thereby rotating the cam lever 4 to drive the type bar toward platen 9.

Latch 6 which is carried by cam lever 4 is'rotated about shaft 10, and accordingly, the ear 31 slides under the lug 30. It will be noted that the bottom or cam edge 28 of latch 6 rides on the cooperating surface 29 of the cam 5 and accordingly, the ear 31 is held in contact with the lug 30 until the cam has rotated far enough to get the ear 31 out from under the lug 30, or to get the fiat cut off surface 29a of cam 5 into engagement with cam edge 28 whereupon the key lever 2 is free for downward movement until it bottoms in its slot 34 of the comb 33. The cut oil": surface 29a usually engages cam edge 28 to permit bottoming of the key lever before ear 31 is slid from under lug 30, but actually it is some combination of these two movements that permits the key lever to bottom. In any event, the point -at which the key lever is free to drop to the bottom of the comb will be called for convenience, the end of function point, and it is depictedas point D' in the graph (Fig. 4).

With referenceto the other positions on the graph, which, incidentally, illustrates the spring forces acting on a key leverv during a print stroke, the point A can be correlated with the solid line, or rest position A of the key lever, as shown in Fig. 3. The end of function point D can be correlated with the dotted line position D of the key lever (Fig. 3); while the F point of the graph can be correlated with the dash-dot position F of the key lever (Fig. 3).

A point E which is also represented on the graph is a clearance point which is provided in view of the fact that all key levers will not finish their function or be released for bottoming at exactly the same point. The relationship of clearance point E will hereinafter be explained.

In its three principal positions, the key lever moves from rest position, A to its end of function position D (or clearance point E), and then to position F wherein the key lever bottoms in the guide comb. Normally, the key lever would be free to move to the comb bottom only in opposition to the restoring spring 38. This movement is represented by dotted line joining points E'G' on graph. In accordance With this invention, however, and in the particular embodiment shown in Fig. 1, it will be noted that acantilever type spring 42 having a higher constant than spring 38 has been positioned in a mounting member 44 so that the free end ofthis spring will engage the butt 40 of the key lever just after it has reached its end of function position D. Then in travelling from D (or clearance position E) to bottoming position F, the butt member 40 will deflect the spring 42.

As the spring 42 is deflected, the operator feels the increase in force necessary to move the key lever to the bottom of the guide 33, and this pressure increase, in effect, gives a timing pulse to the finger letting it know that the useful work of that key lever has been completed. This movement in opposition to the spring 42 is depicted by line EF' on the graph. It .should'be noted that while the key lever is deflecting the spring 42, the latter is storing energy which will be released as the key lever is returned towards its normalposition. In releasing this stored energy, the spring 42, through the key lever gives a lift to the operators finger thereby decreasing the effort she would have to expend to raise her finger manually, and by analogy, a springboard .tou'ch system is provided for the operator.

In dealing with a structure of this sort, it is important that the key lever be moved through its functioning stroke against a minimum amount of force, and accordingly, it has been proven through years of experience, that it is not advisable to use a return spring 38 having any greater force than is necessary for restoring the key lever from its operative to its inoperative position. However, it must be recognized that there is distinction between the movement of a key lever during which it performs a function, and the additional movement of :the key lever during which itv serves no useful purpose. In moving through this latter distance, the operator simply wastes time,-and the sooner her finger is removed from the key lever, the sooner that it can be used to operate another one. Accordingly, the second or cantilever type spring 42, in order to meet the requirements of-this invention, must be so positioned that it does not engage the key lever until after it has performed its useful function. Further, the spring 42 must have suchproperties that it does not offer sudden shock load tothe key lever in its movement from position D.to position'F.

It is important to note too, in Fig. 3, of this'applica tion thatspring 42 is positioned to take effect at position E, while the key lever actually completes its function=at position D. This allowance is provided in view of'the fact that all key levers will not be released for bottoming at exactly the same position. By positioning thespring under all conditions has dropped off and is through with its function.

In the operating of a typewriter provided'with'this improved springboard'feature, it has been found that the speed of the typist has been increased as much as 20%. The typist feels that certain rhythm has been provided with the springboard feel and further a bounce is given to the finger in its movement to the next key lever.

' While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. In a type bar drive mechanism having a key lever for actuating the same, means pivotally supporting said key lever at one end, means mounting the opposite end of said key lever for rocking movement from an inoperative position through an actuating .range and beyond it in the same direction into a non-functioning stage, .said mounting means comprising a slotted guide comb positioned for guiding saidkey lever through its entire range of'travel, a first spring interconnecting said guide comb and said key lever for restoring said key lever to its inoperative position after it has been displaced therefrom, and a second spring positioned for engagement with said key lever after it has passed through its functioning stage to resist resiliently travel of said key lever in its non-functioning stage.

2. In a type bar drive mechanism having a key lever for actuating the same, means pivotally supporting said key lever at one end, means mounting the opposite end of said key lever for rocking movement from an inoperative position through an actuating range and beyond it in the same direction into a non-functioning stage, said mounting means comprising a first spring positioned forengagement with said key lever through its entire range of travel and for restoring said key lever to its inoperative position after it has been displaced therefrom, and a second spring positioned for engagement with said key lever only in its non-functioning stage, said second spring being unloaded until it has been engaged by said key lever but being capable of storing energy during movement of said key lever in said non-functioning stage in one direction and for restoring said energy to said key lever in its movement in said non-functioning stage in the opposite direction thereby providing a springboard touch feel for said key lever.

3. A type bar drive mechanism having a key lever for actuating the same, means pivotally supporting said key lever at one end, means mounting the opposite end of said key lever for movement from an inoperative position through an actuating range and beyond it in the same direction into a non-functioning stage, said mounting means comprising a slotted guide comb positioned to guide said movable end of said key lever through its entire range of travel, a first spring positioned for engagement with said movable end of the key lever through its entire range of travel and for restoring said key lever to its inoperative position after it has been displaced therefrom, a second spring having a greater spring constant than said first spring, and means mounting the same adjacent said guide comb for continual engagement with the movable end of said key lever in its non-functioning stage thereby storing energy while resiliently resisting travel of said key lever in one direction in this latter stage and restoring the energy to said key lever while it travels in the opposite direction in its non-functioning stage.

4. In a type bar drive mechanism having a key lever' for actuating the same, pivot means mounting said key lever at one end, means mounting the opposite end of said key lever for rocking movement from an inoperative position through an actuating range and beyond it in the same direction into a non-functioning stage, said mounting means comprising a comb having slots therein to guide said key lever through its entire range of travel, resilient means mounted on said guide comb for continual engagement with the movable end of said key lever and for restoring said key lever to its inoperative position after it has been displaced therefrom, a cantilever type spring having a free end, means mounting said cantilever spring adjacent said guide comb for interengagement with the free end of said spring and said key lever after the latter has passed completely through its actuating range and for continual engagement therewithin its non-functioning stage, said cantilever spring being adapted to absorb energy while said key lever is passed in one direction in its non-functioning stage and to restore energy to said key lever and through it to an operators finger when said key lever is travelling in the opposite direction in its nonfunctioning stage thereby to provide a springboard touch feature for a key lever.

5. In a typewriter having a type bar, an actuating mechanism therefor comprising in combination, a cam lever operatively connected to said type bar, a power roll, a cam pivotally mounted on said cam lever and engageable with said power roll for actuating said cam lever to drive said type bar to printing position, yieldable means for holding said cam normally in a position free of said power roll, a trip latch mounted on said cam lever for pivotal movement to a tripping position wherein said cam is forced into engagement with said power roll to initiate a type bar print stroke, a key lever engageable with said trip latch for rocking the latter to a tripping position, and means supporting one end of said key lever for pivotal movement from an inoperative position to a tripping position and beyond it in the same direction into a non-functioning stage comprising a slotted guide comb positioned for guiding said key lever through its entire range of travel, a first spring interconnecting said guide comb and said key lever for restoring said key lever to its inoperative position after it has been displaced therefrom, and a second spring positioned for engagement with said key lever after it has passed through its tripping stage to resist resiliently travel of said key lever in its non-functioning stage.

References Cited in the file of this patent UNITED STATES PATENTS 1,923,596 Vanderwerp Aug. 22, 1933 2,043,393 Pasinski June 9, 1936 2,714,948 Schremp et al. Aug. 9, 1955 2,723,740 Toeppen Nov. 15, 1955 

